Electrically powered artificial lighting has become ubiquitous in modern society. Electrical lighting devices are commonly deployed, for example, in homes, buildings of commercial and other enterprise establishments, as well as in various outdoor settings.
In conventional lighting devices, the luminance output can be turned ON/OFF and often can be adjusted up or dimmed down. In some devices, e.g. using multiple colors of light emitting diode (LED) type sources, the user may be able to adjust a combined color output of the resulting illumination. The changes in intensity or color characteristics of the illumination may be responsive to manual user inputs or responsive to various sensed conditions in or about the illuminated space. The optical distribution of the light output, however, typically is fixed. Various different types of optical elements are used in such lighting devices to provide different light output distributions, but each type of device has a specific type of optic designed to create a particular light distribution for the intended application of the lighting device. The dimming and/or color control features do not affect the distribution pattern of the light emitted from the luminaire.
To the extent that multiple distribution patterns are needed for different lighting applications, multiple luminaires must be provided. To meet the demand for different appearances and/or different performance (including different distributions), a single manufacturer of lighting devices may build and sell thousands of different luminaires.
Some special purpose light fixtures, for example, fixtures designed for stage or studio type lighting, have implemented mechanical adjustments. Mechanically adjustable lenses and irises enable selectable adjustment of the output light beam shape, and mechanically adjustable gimbal fixture mounts or the like enable selectable adjustment of the angle of the fixture and thus the direction of the light output. The adjustments provided by these mechanical approaches are implemented at the overall fixture output. Such adjustments provide relatively coarse overall control and are really optimized for special purpose applications, not general lighting.
There have been more recent proposals to develop lighting devices offering electronically adjustable light beam distributions, using a number of separately selectable/controllable solid state lamps or light engines within one light fixture. In at least some cases, each internal light engine or lamp may have an associated adjustable electro-optic component to adjust the respective light beam output, thereby providing distribution control for the overall illumination output of the fixture.
Although the more recent proposals provide a greater degree of distribution adjustment and may be more suitable for general lighting applications, there may be room for still further improvement in the degree of adjustment supported by the lighting device.